The present invention pertains to fuel cells, and more particularly to a fuel processor and integrated fuel cell fabricated utilizing ceramic technology for improved size and performance benefits.
Fuel cells in general, are xe2x80x9cbattery replacementsxe2x80x9d, and like batteries, produce electricity through an electrochemical process without combustion. The electrochemical process utilized provides for the combining of hydrogen with oxygen from the air. The process is accomplished utilizing a polymer electrolyte membrane (PEM) which conducts protons sandwiched between two electrodes, namely an anode and a cathode. Fuel cells, as known, can provide perpetual electricity as long as fuel and oxygen is supplied. Hydrogen is typically used as the fuel in fuel cells for producing the electricity and it can be processed from methanol, natural gas, petroleum, ammonia, or stored in metal hydrides, carbon nanotubes, or as pure hydrogen. Reformed hydrogen fuel cells (RHFCs) utilize hydrogen fuel processed from liquid or gaseous hydrocarbon fuels, such as methanol, using a fuel reformer.
Reformed hydrogen fuel cells preferably utilize methanol that is reformed into hydrogen as a fuel source. Methanol is the preferred fuel for use in fuel reformers for portable applications because it is easier to reform into hydrogen gas at a relatively low temperature compared to other hydrocarbon fuels such as ethanol, gasoline, or butane. The reforming or converting of methanol into hydrogen usually takes place by one of three different types of reforming. These three types are steam reforming, partial oxidation reforming, and autothermal reforming. of these types, steam reforming is the preferred process for methanol reforming because it is the easiest to control and produces a higher hydrogen output, at a lower temperature, thus lending itself to favored use. During steam reforming, raw methanol is catalytically converted, with the application of heat, to a hydrogen enriched fuel gas for use with fuel cells.
Fuel reformers have been developed for use in conjunction with fuel cell devices, but they are cumbersome and complex devices consisting of several discrete sections connected together with gas plumbing and hardware to produce hydrogen gas, and are thus not suitable for portable power source applications. To date, no fuel reformers have been developed utilizing ceramic monolithic structures in which the miniaturization of the reformer can be achieved. Laminated ceramic components, utilizing ceramic technology, are now commonly being developed for use in microfluidic chemical processing and energy management systems. Monolithic structures formed of these laminated ceramic components provide for components that are inert and stable to chemical reactions and capable of tolerating high temperatures as well as providing for miniaturized components, with a high degree of electronic circuitry or components embedded or integrated into such a ceramic structure for system control and functionality. Additionally, the ceramic materials used to form ceramic devices including microchannels are considered to be excellent candidates for catalyst supports in microreactor devices for generating hydrogen used in conjunction with miniaturized fuel cells.
Accordingly, it is an object of the present invention to provide for a miniaturized fuel processor that provides for the reforming of a fuel to a hydrogen( )enriched fuel gas for use in conjunction with an integrated fuel cell.
It is yet another object of the present invention to provide for a monolithic structure for the reforming of a fuel to a hydrogen enriched gas.
It is still another object of the present invention to provide for a monolithic structure that is formed utilizing ceramic technology, thereby providing for the integration of a plurality of internal plumbing interconnections and electrical circuitry and connections.
It is another object of the present invention to provide for a fuel processor that is miniaturized for use in conjunction with an integrated fuel cell for portable device applications.
The above problems and others are at least partially solved and the above purposes and others are realized in a fuel processor and integrated fuel cell including a three-dimensional multilayer ceramic carrier structure defining a fuel reformer and including an integrated fuel cell stack. The fuel reformer includes a vaporization zone and a reaction zone including a reforming catalyst. The ceramic carrier further includes an integrated heater thermally coupled to the vaporization and reaction zones, an inlet channel for liquid fuel and an outlet channel for hydrogen enriched gas. The fuel processor is formed utilizing ceramic technology in which thin ceramic layers are assembled then sintered to provide miniature dimensions in which the encapsulated catalyst converts or reforms inlet fuel into a hydrogen enriched gas.